Why am I running lean??

[chuckycheese]

My bike seems to be running lean and I simply can't figure out why. Here are the symptoms.
1. Slow warming up
2. Fairly steady backfire upon reving up the engine and also when backing off of the throttle. It seems to be only on numbers #3 and #4.
3. My plugs aren't charred or ashen but they're definitely white.

I've adjusted the airscrews a million times and I just can't seem to get rid of it. I should also mention that the bike accelerates and runs extremely well. It doesn't "miss", idles steadily at 900 RPM (after warming up for 10 minutes).

I don't think there's a chance that I have an air leak because my connections are good and my rubber boots truly look as good as new. Any and all ideas would be welcomed!:? Thanks!!:-D

[chef1366]

Bump up your Pilot Jets one(2.5). If you pull well on full throttle I wouldn't mess with the Main Jet. Have you done throttle chops to determine where you're running lean. It does sound like your pilot circuit with the hard starting.

[chuckycheese]

Thanks

Well, it starts really easily..as it always has. Also, it runs so well after a few minutes..it just seems like all is not well because of the sputtering and backfireing....I'm not about to pull off my carbs as of yet!8-[ I've done that not too long ago and gave them a complete overhaul and I'm satisfied they're looking good. (At least, I hope so!!)

[chuckycheese]

Update

I think I've figured out my problem....and it occurred to me about 3:00am while I was trying to sleep. I have a Pingel petcock so my vacuum tube is capped. I figured maybe the cap was rotten. Sure enough, it was and was leaking.

I replaced it and the bike runs just about perfect. I think the only reason it's off a little bit is because of all the adjustments I made...it should be easy to straighten out.\\/

[chef1366]

With experience it's always easy to overlook a simple solution because we think way too much.

[chuckycheese]

True

That's very true! I could have kicked myself because I should have thought of that the very first thing. After all, I'm the one that put on the Pingel so it should have 'popped into my head' right away.

I'd like to say this is the first time I've done something like this but it's about the 23rd...or so.

[chef1366]

Twenty-third? Could that be some kind of record\\/